fix(mcp): extract EmbeddedResource content blocks from tool results

[kingofkillers91]

Problem

MCP servers that return type="resource" content blocks (EmbeddedResource in the MCP SDK) have their results silently dropped by Hermes' MCP client. The client only extracts text from TextContent and ImageContent blocks, ignoring EmbeddedResource blocks entirely.

Affected tools: GitHub MCP get_file_contents (v1.4.0+), Playwright MCP, filesystem servers, and any MCP server that embeds file content as resource blocks.

Symptom: get_file_contents returns "successfully downloaded text file (SHA: ...)" — the metadata text block — but the actual file content in the resource block is dropped. The agent sees an empty result.

Root Cause

tools/mcp_tool.py extracts content from tool results in three places, all using hasattr(block, "text") only:

1. Main tool result loop (~line 3194) — iterates result.content, extracts .text and image blocks, drops everything else
2. Error text extraction (~line 3174) — same pattern for error responses
3. _extract_tool_result_text() (~line 909) — extracts text from ToolResultContent blocks, same gap

The MCP spec defines EmbeddedResource with type="resource" where the payload lives at .resource.text (or .resource.blob for binary). These blocks have no top-level .text attribute.

Fix

Patch all three extraction points to also check for hasattr(block, "resource") and extract .resource.text:

# Added before the image_tag fallback:
if hasattr(block, "resource"):
    resource = block.resource
    if hasattr(resource, "text") and resource.text:
        parts.append(resource.text)
        continue

Verification

Before patch:

mcp_github_get_file_contents → {"result": "successfully downloaded text file (SHA: abc123)"}

After patch (tested with GitHub MCP v1.4.0):

mcp_github_get_file_contents → {"result": "successfully downloaded text file (SHA: abc123)\ninterface:\n  display_name: \"Loop Library\"..."}

Content from the resource block is now included alongside the metadata text.

Related

• Fixes MCP tool results with EmbeddedResource (resource) blocks are silently dropped #30601
• Supersedes the approach in [Feature]: Fix for: Hermes Agent Silently Drops EmbeddedResource Content Blocks from MCP Tool Results #26972 (closed without merge)
• Distilled from the fix proposed by @raumzeit77 in [Feature]: Fix for: Hermes Agent Silently Drops EmbeddedResource Content Blocks from MCP Tool Results #26972

[alt-glitch]

Duplicate of #31356 — same MCP EmbeddedResource (type=resource) text-extraction fix in tools/mcp_tool.py. #31356 is the canonical open PR for this; prior duplicates: #13736, #18118, #3655 (all closed), originating issue #26972. The fix here is the same resource.text extraction gap. Marking duplicate of the canonical open PR.

[teknium1]

This is now fixed on main via PR #64556 (salvaged from #64061, which materializes binary blobs to the document cache and covers ResourceLink/Audio in addition to embedded resource text). Your fix addressed the same underlying bug — thanks for the contribution, and sorry we couldn't take this one; five PRs ended up targeting the same dropped-resource-block issue.